Many cardiac tachyarrhythmias are caused by conduction defects which interfere with the normal propagation of electrical signals in a patient's heart. These arrhythmias may be treated electrically, pharmacologically or surgically. The optimal therapeutic approach to treat a particular tachyarrhythmia depends upon the nature and location of the underlying conduction defect. For this reason electrophysiologic mapping is used to explore the electrical activity of the heart during a tachyarrhythmic episode. The typical electrophysiologic mapping procedure involves positioning an electrode system within the heart. Electrical measurements are made which reveal the electrical propagation of activity in the heart. If ablation is the indicated therapy then a therapy catheter is positioned at the desired location within the heart and energy is delivered to the therapy catheter to ablate the tissue.
There are numerous problems associated with these electrophysiologic diagnostic and therapeutic procedures. First the testing goes on within a beating heart. The motion of the diagnostic catheter and treatment catheter can injure the heart and provoke bouts of arrhythmia which interfere with the collection of diagnostic information. During the delivery of ablation therapy it is common to use fluoroscopic equipment to visualize the location of the catheters. Many physicians are concerned about routine occupational exposure to X-rays. In addition, the traditional mapping techniques do not provide a high resolution view of the electrical activity of the heart which makes it difficult to precisely locate the source of the arrhythmia.